Polybutadiene-crotonic adducts



linite ronvnuranrnmn cnorornc Annnctrs Joachim, Dazzi, Dayton, Gino, assignor to Monsanto Chemical Qompany, Louis, Ma, 21 corporationof Delaware N Drawing. Application May 27, 1953 SerialNo. 357529- 8 Claims. ((-11. 26il-94.7)

This invention relates to high molecular weight adducts and more particularly provides linear polymeric compounds having a plurality of carboxylate radicals and a process for producing the same.

An object of the invention is the provision of'new and useful polycarboxylates. Another object of the invention is the preparation of polycarboxylates from readily available polymeric materials. Still another object of the invention is-the preparation of linear polycarboxylates from butadiene hydrocarbon polymers. A further object of the invention is to provide for the coatings, synthetic resins and plastics, plasticizer, rubber and textile industries a new class of polymeric materials having a high content of carboxylic radicals.

These and other objects of theinvention hereinafter disclosed are provided by the following-invention Wherein there are prepared adducts of (l) a polymeric bntadiene hydrocarbon with (2) a compound selected from the class consisting of crotonic anhydrid'e, crotonic acid, andesters of crotonic acid having the formula cincmcnooon in which R is selected from theclass consisting of alkyl radicals of from 1 to 8 carbon atoms, alkoxyalkyl radicals of from 2 to 8 carbon atoms, alhylmercaptoalkyl radicals of from 4 to- 8 carbon atoms, alicyclic radicals of'from 3 to 6 carbon atoms, aryl radicals of from 6 to 12 carbon atoms and aralkyl radicals of from 7 to 11 carbon atoms and the furfuryl and tetrahydrofurfuryl radicals, one mole of'said anhydride, acid or ester being combined at each of at least percent of theolefinic units of said polybutadiene.

Esters having the above formula and useful for the present purpose include the alkyl crotonates such as methyl, ethyl, isopropyl, n-propyl, n-butyl, tert-butyl, isoamyl, n-hexyl, n-heptyl or isoocytl crotonate; the alkoxyalkylcrotonates' such as Z-methoxyethyl, 3-ethoxy-n-propyl or 4-butoxybutyl crotonate; the hydroxyalkyl ester-s such as Z-hydroxyethyl or 3-hydroxypropyl crotonate, the alicyclic esters such as cyclopropyl, cyclopentyl or cycloheX-yl'crotonate; themercaptoalkyl esters such as 4-ethylmercaptobutyl crotonate; thearyl esters such as phenyl', fi-naphthyhor Z-xenyl'crotonate; the aralkyl esters such as benzyl, or Z-phenyletnyl' crotonate; iurfuryl or tetrahydrofurfuryl crotonate, etc.

Butadiene hydrocarbon polymers which add to crotonic anhydride, crotonic acid or the-above crotonates are solid or normally liquid polymers of butadiene hydrocarbons such as 1,,3-butadiene, isoprene, piperylene; dimethylbutadiene, Z-methylpentadiene, 2 ethylhexadiene and the like. The presently useful polymers may also be polymer-3 derived by copolyrnerizationof two or more dif-'- ferent butadiene hydrocarbons, e. g., from a mixture of butadiene and piperylene.

Reaction of the butadiene polymers with the crotonic compounds to form adducts takes place readily by heating the polymerwith the acid, anhydride or ester in the presence orrabsence of an inert diluent:or'polymertsolveut at ordinary or superatmospheric pressures. When operating at atmospheric pressure, temperatures of from, say,

2,336,586 Patented May 27, 1958 C. to 300" C.. and preferably of from 1.80 C. to 250 C. are used. An inhibitor of polymerization may be incorporated into. the reaction mixture. The. number of carboalkoxy groups introduced into the liquid polymer molecule depends upon the dieneconte-nt of the polymer, upon the nature of the individual crotonic compound used, and upon the reaction conditions employed. Genera-11y, operation within the higher temperature ranges, i. e-., at temperaturesof above,,say, 180* C., under superatm'ospher-ic pressure, and below the decompositionpoint of any of the reactants leads to the-introduction of: more carboalkoxy groups than does operation at the lower temperatures. The use or superatrnospheric pressure is advisablev when working with the. low boiling esters, i-. e., with ethyl, butyl or amyl crotonate; Thedegree of carboalkoxylation also depends upon theindividualcrotonate employed. Usually, crotonic anhydride, crotonic acid. or the: lower alkyl'esters are more reactive than either the higher alkyl or the higher alkoxyalkyl esters. In view of the: effect of the; reaction conditions and nature of the individual, crotonic compound upon the extent of carboalkoxylatiomit' is recommended that for each initial run there be experimentally determined the operating conditions which shouldbe observed for obtaining-thedesired degree of carboalkoxyl'ation.

The quantity ofcrotonic compound presentin the adduct will: also depend upon its availability in the reaction mixture. Obviously, "r. the: formation; of. adducts in which at least one mole. of the crotonic compound has added to each olefinic unit of the liquid polymer, thecalculated amount of the acid, a-nhydrid'e. or ester'may be present in the reaction mixture.

The reaction may he efi ected in the presence or absence of an inert solvent or. diluent. Particularly, when working with the liquid polymers, no. extraneous solvent or diluent need be employed. However, with the solid polymers and, in some instances with the liquid polymers, it may be advantageous to work with a solution of the polymer in an inert, extraneous diluent or solvent, e. g., a liquid hydrocarbon or a liquid derivative thereof such as benzene, xylene, nitrobenzene'or dichlorobenzene, a high-boiling aliphatic hydrocarbon such as kerosene, halogenat'edhydrocarbons such as chloroform or tetrachloroethane, etc. Whenworking atatmospheric pressure, such diluent is generally removed before reaction of the polymer with the ester occurs, due to the high temperatures used;

Whenworking with crotonic anhydrideor crotonic acid, the adducts obtained have free anhydride or carboxy groups. These may be converted to salts or esters'by treatment with inorganic, bases or alcohols.

The contemplated use of the polybutadiene-crotonic adducts will determine the extent of carboxylation or carboa'lkoxylation desired. Adducts' having alow proportion. of; carboaikoxy radicals. are. advantageously ems ployedas-adhesives, particularly asadhesives'in bonding ofz'cellulosic materials. Adducts having a higher'proportionao'r car-boalkoxy. groups, the other hand, are useful as synthetic resin plasticizers; Adducts having free anhyd'ridelor'carooxy. groups areuseful for conversion into surface-active salts. thereof.

That the: polybutadiene-crotonate: reaction products are adducts rather'than blends of the polybutadiene and polymeric" ester may be-evidence'd by hydrolysis of the reaction products to completely water-soluble materials. Thus, upon heating the adducts with aqueous alkali metal hydroxides;or ammonia, they may beentirely converted tozwatensoluble salts. Treatment of the salts with dilute mineral. acids yie-lds: the free polyearboxylie acids. The present invention thus'provides not only the estergadducts; but also a newseries. of polycarboxylicacids: and their alkali metal or ammonium salts:

, 3 The present invention is further illustrated, but'not limited, by the following examples:

, Example 1 V V To a 3-liter, stainless steel bomb there Werecharged 710 g. (5 moles) of butyl crotonate, 1 g. of hydroquinone and 108 g. (2 moles) of a liquid polybutadiene, a redorange viscous material having a molecular weight of approximately 1500, analyzing 89.2% C, 11.19% H and 7 having a viscosity of 880 centipoises at 50 C. as determined by the Brookfield method at a spindle rate 'of l R. P. M. The contents were heated under a nitrogen pressure of 200 p. s. i. for 10 hours at 200 C: 'The re-' action mixture was then distilled at 25-30 mm; of Hg pressure'to remove unreacted butyl'crotonate and then 'heated at l-2 mms at an oil-bath temperature of 180 'C. to give a total'of 238.1 g. of unreacted'butyl crotonate. There'was thusrobtained as residue 162 g. of the liquid polybutadiene-butyl crotonate adduct n 1.5150 analyzing 83.50% C, 10.53% H and (by difference) 5.97% O. The composition of the residue thus corresponds to an adduct in which 108 g. of the polybutadiene is combined with 162 minus 108 or 54 g. of butyl crotonate. Based on the molecular weight of a butene unit as 54 and that of butyl crotonate as 142 in the present adduct 2 butene units have combined with 54/142 or 0.39 mole of butyl crotonate, i. e., the residue represents an adduct in which an averageof 0.195 mole of butyl crotonate has com- 7 charged 'to a 500 rnl., 3-necked fiask'which was equipped with stirrer, thermometer and a Dean-Stark trap carry ing a reflux condenser. The mixture was refluxed (212- 201 'C.) at an oil bath temperature of 240-250 C. 'for' 13 hours and then submitted to distillation at a pressure of 1 mm. of Hg and an oil bath temperature .of

220 C. The residue (110 g.) changed to a brittle solid upon cooling. It was ground to a yellowish brown powder. Analysis of the powder gave 75.64% C, 8.18% H and (by diflerence) 16.18% 0, indicating introduction of the anhydride oxygen into the polymer.

which 110 g. minus 32.4 g., or 77.6 g. of crotonic anhydride had added to 32.4 g. of the polymer. The pres- .ent product is thus an adduct in which an average of 0.84 mole of crotonic anhy ride Was'added to each peated butene unit of the polybutadiene.

. 7 Example Hydrolysis of the.polybutadiene-crotonic anhydride ad- Based on the weight increase, the powdered solid is an adduct in duct of Example 2 was accomplished by refluxing, for

3 hours 15 g. of the adduct in 200 g. of a solution of 4 g. of sodium hydroxide in aqueous ethanol. Upon removal of the ethanol by concentrating the're fluxed reaction mixture to a volume of m1., there was obtained a clear, easily foaming, aqueous solution of the sodium salt of the hydrolyzed polybutadiene-crotonic anhydride adduct. Hydrolysis of the adduct as here shown to give the completely water-soluble sodium salt shows that addition, rather than polymerization had occurred in the reaction of Example 2.

What I claim is:

' 1. An adduct of 1) a polymer derived only from an aliphatic dienic hydrocarbon of from 4 to 8 carbon atoms with (2) a carboxy compound selected from the class consisting of crotonic anhydride, crotonic acid, and an ester of crotonic acid having the .formula CH CH:CHCOOR in which R is selected from the class consisting of alkyl radicals of from 1 to 8 carbon atoms,-alkoxyalkyl radicals of from 2 to 8 carbon atoms, alkylmercaptoalkyl radicals of from 4 to 8 carbon atoms, alicyclic radicals of from 3 to 6 carbon atoms, aryl radicals of-from 1 to 12 carbon atoms and arallgyl radicals of from 4 to 14 carbon atoms and the furfuryl and tetraliydrofurfuryl radicals, one mole of said carboxy compound being cornbilled at each of at least 5 percent of the olefinic units of said polymeric hydrocarbon, said adduct havingbeen prepared by heating the polymer with the carboxy compound at-a temperature of from C. to 300 C.

2. An adduct of polybutadiene with an alkyl crotonate in which the alkyl radical has from 1 to 8 carbon atoms, one mole of said crotonate being combined at each of at least 5 percent of the olefinic units of said polybutadiene, said adduct having been prepared by heating-the poly- .butadiene with the crotonate at a temperature of, from 160 C. to 300 C.

3. An adduct of liquid polybutadienewith butyl crotonate, one mole of said crotonate being combined at each of atleast 5 percent of the olefinic units of said polybutadiene, said adduct having been prepared by heating the polybutadiene with the crotonate at a temperature of from 160 C. to 300 C.

4. An adduct of liquid polybutadiene and; crotonic anhydride, one mole of said anhydride being combined at each of at least 5 percent of the olefinic units of said polybutadiene, said adduct having been prepared by heat-' ing the polybutadiene with the anhydride at a tempera .ture of from 160 C. to 300 C.

5. The process which comprises heating, at a temperature of from 160C. to 300 C., a polymer derived only from an aliphatic'dienic hydrocarbon'of from 4 t0 8 carbon atoms with a carboxyv compound selected from the class consisting, of crotonic anhydride, crotonic acid, and an ester of crotonic acid having the formula CH CH:CHCOOR in which R is selected from the class consisting of alkyl radicals of trorn 1 to 8 carbon atoms, alkoxyalkyl radicals of from 2 to 8 carbon atoms, -alkylmercaptoalkyl radicals of from 4 to 8 carbon atoms, alicyclicradicals of from 3 to 6 carbon atoms aryl radicals of from. 1 to 12 carbon atoms and aralkyl radicals of from 4 to 14 carbon atoms and the furfuryl and tetrahydrofurfuryl radicals, and recovering from the resulting'reaction prod uct an adduct in which one mole of said. carboxy compound is combined at each of at least 5 percent of the olefinic units of said polymeric hydrocarbon.

6. The process which comprises heating, at a tempera- .ture of from 160 C. to 300 C., polybutadiene with an alkyl crotonate in which the alkyl radical has from 1 to 8 carbon atoms and recovering from the resulting reaction 7 product an adduct in which one mole of 'said crotonate'. is combined at each ofat least 5 percent of'the olefinic units of said polybutadiene.

7. The process which comprisesheating, at a temperature of from 160 C; to 300 C., a liquid polybutadiene with butyl crotonate and'recovering from there,

sulting reaction product an adduct in which 1 mole of said crotonate is combined at each of at least 5 percent of the .olefinic units of said polybutadiene. V

V 8. The process which comprises heating, at a temperature of from 160 C. to 300 C., a liquid polybutadiene with crotonic anhydride and recovering from the resulting reaction product an adduct in which 1 mole of said anhydride is combined at each of at least 5 percent of the olefinic units of said polybutadiene.

References Cited in the file of this patent UNITED STATES PATENTS 2,142,980 Huijser et a1. Ian. 3, 1939 

1. AN ADDUCT OF (1) A POLYMER DERIVED ONLY FROM AN ALIPHATIC DIENIC HYDROCARBON OF FROM 4 TO 8 CARBON ATOMS WITH (2) A CARBOXY COMPOUND SELECTED FROM THE CLASS CONSISTING OF CROTONIC ANYDRIDE, CROTONIC ACID, AND AN ESTER OF CROTONIC ACID HAVING THE FORMULA 